Question

Define the following terms: acids, bases, oxoacids, oxoanions, and hydrates.

Short answer

Acids release H⁺ ions; bases release OH⁻ ions; oxoacids contain H, O, and a non-metal; oxoanions are negative ions from oxoacids; hydrates include water molecules in their structure.

Step-by-step solution

Define Acids

Acids are substances that release hydrogen ions (H⁺) when dissolved in water. They possess a sour taste, can conduct electricity when in solution, and turn blue litmus paper red. Acids often have a pH less than 7.

Define Bases

Bases are substances that release hydroxide ions (OH⁻) when dissolved in water. They have a slippery feel, bitter taste, can conduct electricity, and turn red litmus paper blue. Bases generally have a pH greater than 7.

Define Oxoacids

Oxoacids are compounds consisting of hydrogen, oxygen, and another element, usually a non-metal. These acids contain at least one or more peroxy groups (e.g., H₂SO₄, HNO₃) and ionize in water to produce hydrogen ions and an oxoanion.

Define Oxoanions

Oxoanions are negatively charged ions composed of oxygen and another element. They are the anionic (negative ion) counterpart of the oxoacids, formed when the hydrogen ions are removed (e.g., sulfate SO₄²⁻ from sulfuric acid H₂SO₄).

Define Hydrates

Hydrates are compounds that include water molecules bound to a metal center or incorporated into the crystal structure. These water molecules can be removed through heating, which changes the structure and properties of the material.

Key concepts

Acids

Acids are fascinating substances that play a significant role in chemistry and everyday life. When dissolved in water, acids release hydrogen ions \((H^+)\), making them capable of conducting electricity. This is because the hydrogen ions are highly reactive.
The acidic solutions tend to have a sour taste, which is why they are present in foods like lemons and vinegar. In terms of pH, acids have a value less than 7. The pH scale measures the acidity or basicity of a solution, with lower numbers indicating higher acidity.
Acids also have the property of turning blue litmus paper red, a simple test to identify an acidic solution. Examples of common acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and citric acid.

Bases

Bases are the chemical opposites of acids. In water, bases disassociate to release hydroxide ions \((OH^-)\). This property makes them conduct electricity too, similar to acids. Bases usually have a bitter taste and feel slippery to the touch, like soap.
These substances have a pH value greater than 7, indicating their basic nature. One intriguing property of bases is their ability to turn red litmus paper blue, providing an easy way to test for basicity.
Some common examples of bases include sodium hydroxide (NaOH), often used in cleaning products, and calcium hydroxide, found in limewater.

Oxoacids

Oxoacids are a unique category of acids composed of hydrogen, oxygen, and another element, typically a non-metal. A distinctive feature of oxoacids is they contain at least one or more peroxy groups.
In solution, oxoacids ionize to release hydrogen ions \((H^+)\) and an oxoanion. The most well-known oxoacids include sulfuric acid \((H_2SO_4)\) and nitric acid \((HNO_3)\).
These acids are crucial in various chemical processes and are widely used in industry, such as in fertilizers and explosives. They exhibit the typical acidic properties, like changing the color of litmus paper and having a low pH.

Oxoanions

Oxoanions are the anionic forms of oxoacids, created when hydrogen ions are removed from the oxoacid. These ions carry a negative charge and consist of oxygen bound to another element.
A clear example is the sulfate ion \((SO_4^{2-})\), derived from sulfuric acid \((H_2SO_4)\). The presence of oxygen often indicates that these ions play an active role in reactions, such as electron transfer or acting as ligands in coordination complexes.
Oxoanions are vital in both chemistry and biology, being part of metabolic pathways and environmental processes like nutrient cycling.

Hydrates

Hydrates are compounds that incorporate water molecules into their crystal structure. This unique property distinguishes them from other substances.
The water, or "water of crystallization," is chemically bonded to the compound, sometimes resulting in dramatic changes to its properties and appearance when removed by heating.
Hydrates are common, with examples such as gypsum (calcium sulfate dihydrate) and copper(II) sulfate pentahydrate. These materials are used in everyday applications, from construction to education, because removing water can often change their texture and volume.